Change in pain intensity = average of daily pain scores from the last 7 days prior to week 12 visit - average of daily pain scores for the last 7 days prior to randomization. Average pain intensity over the last 24 hours was rated on an 11-point numeric rating scale (NRS) ranging from 0 (no pain) to 10 (worst pain imaginable).

Analysis based on Intent-to-Treat (ITT) population; all randomized subjects who received at least 1 dose of double-blind study medication.

Change in pain intensity = average of daily pain scores from the last 7 days prior to each visit - average of daily pain scores for the last 7 days prior to randomization. Average pain intensity over the last 24 hours was rated on an 11-point numeric rating scale (NRS) ranging from 0 (no pain) to 10 (worst pain imaginable).

Analysis based on ITT population; all randomized subjects who received at least 1 dose of double-blind study medication.

Responses are defined as the relative improvement in pain score at week 12 from baseline, calculated from ratings of average pain intensity over the last 24 hours on an 11-point numeric rating scale (NRS) ranging from 0 (no pain) to 10 (worst pain imaginable).

Analysis based on ITT population; all randomized subjects who received at least 1 dose of double-blind study medication.

Treatment failure is defined as study discontinuation due to lack of efficacy or due to adverse event in the double-blind treatment phase.

Analysis based on ITT population; all randomized subjects who received at least 1 dose of double-blind study medication.

Subjects assessed changes in activity, limitations, symptoms, and overall quality of life related to their painful condition since beginning treatment using the Patient Global Impression of Change (PGIC), a balanced 7-point scale from 1 (no change or condition got worse) to 7 (a great deal better and considerable improvement that has made all the difference).

Analysis based on ITT population; all randomized subjects who received at least 1 dose of double-blind study medication.

The Treatment Satisfaction Questionnaire for Medication (TSQM) is a 14-item instrument used to assess the subject's satisfaction with the ability of the study medication to prevent or treat the condition of chronic low back pain (CLBP) for effectiveness, side effects, convenience, and global satisfaction. Scores range from 0 to 100, where a higher score indicates less dissatisfaction (ie, greater satisfaction).

Analysis based on ITT population; all randomized subjects who received at least 1 dose of double-blind study medication.

Subjects assess disability due to back pain using the Roland Morris Disability Questionnaire (RMDQ) consisting of 24 statements of disability. The score of the RMDQ is the total number of items checked, ranging from 0 to 24 with higher scores indicating greater disability.

Analysis based on ITT population; all randomized subjects who received at least 1 dose of double-blind study medication

Subjects were asked to rate their overall satisfaction with their study drug on a 5-point scale ranging from 1 (poor) to 5 (excellent).

Analysis based on ITT population; all randomized subjects who received at least 1 dose of double-blind study medication.

Investigators rated their overall satisfaction with the study drug administered to a given subject on a 5-point scale ranging from 1 (poor) to 5 (excellent).

Analysis based on ITT population; all randomized subjects who received at least 1 dose of double-blind study medication.

Calculated from the use of rescue medication recorded in subject diary as the sum of all rescue medication tablets used in the last 7 days previous to the derived visit, divided by the number of days in this duration where the amount was reported.

Analysis based on ITT population; all randomized subjects who received at least 1 dose of double-blind study medication